Railway vehicle drive unit

ABSTRACT

A railway vehicle drive unit ( 12 ) is a drive unit to rotatably drive a wheel ( 11 ) of a railway vehicle. More specifically, it includes a reducer housing ( 13 ) held on an inner diameter surface of the wheel ( 11 ), and integrally rotating with the wheel ( 11 ), an input side rotation member ( 14 ) connected to a drive source, a reducing mechanism ( 15 ) to reduce rotation speed of the input side rotation member ( 14 ) and transmit it to the reducer housing ( 13 ), a fixed member ( 23 ) arranged in the reducer housing ( 13 ) and connected and fixed to a vehicle body, axle bearings ( 24 ) and ( 25 ) to rotatably support the reducer housing  13  with respect to the fixed member ( 23 ), and lubricant oil circulating mechanisms ( 32 ) and ( 33 ) to circulate a lubricant oil between the reducing mechanism and the axle bearings ( 24 ) and ( 25 ).

TECHNICAL FIELD

The present invention relates to a railway vehicle drive unit and moreparticularly, to a railway vehicle drive unit capable of driving rightand left wheels independently.

BACKGROUND ART

A conventional railway vehicle drive unit is disclosed in JapaneseUnexamined Patent Publication No. 2007-230508, for example. The railwayvehicle drive unit disclosed in this document includes a motor, and areducer to reduce rotation speed of the motor and transmit it to awheel.

In this railway vehicle drive unit, a cycloidal reducer which is compactin size and implements a high reduction ratio is used to generate torquerequired to run a railway vehicle, and to provide a large passengercompartment space. More specifically, it is composed of an input shaftintegrally rotating with the motor, a curved plate rotatably supportedby an eccentric part provided in the input shaft, an outer pin togenerate rotation motion of the curved plate by engaging with aperiphery of the curved plate, and an inner pin to convert the rotationmotion of the curved plate to revolution motion and transfer it to thewheel.

According to the above reducer, the components rotate while they are incontact with each other, so that a lubricant oil to lubricate contactparts between them is needed. However, the lubricant oil in the reduceris moved toward the radial outer side due to centrifugal force generatedby the rotation, the lubricant oil is likely to run short in thevicinity of the input shaft (on the radial inner side). Meanwhile, whenthe lubricant oil sealed in the reducer is increased to ensure alubricant oil amount around the input shaft, heat generation isincreased due to agitation resistance, and a torque loss of the reduceris increased.

In addition, since the lubricant oil sealed in the reducer spreads alongan inner diameter surface of a casing due to the centrifugal forcegenerated by the rotation of the input shaft and the like, an oilsurface height when the reducer is operated is lower than that when itis stopped. That is, the problem is that the lubricant oil amount runsshort in the vicinity of the input shaft when the reducer is operated.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a railway vehicledrive unit superior in lubrication performance, by keeping a constantoil surface height of a lubricant oil.

It is another object of the present invention to provide a railwayvehicle drive unit in which heat generation and torque loss aredecreased, and a lubrication performance is improved.

A railway vehicle drive unit according to the present invention is adrive unit to rotatably drive a wheel of a railway vehicle. Morespecifically, it includes a reducer housing held on an inner diametersurface of the wheel, and integrally rotating with the wheel, an inputside rotation member connected to a drive source, a reducing mechanismto reduce rotation speed of the input side rotation member and transmitit to the reducer housing, a fixed member arranged in the reducerhousing, and connected and fixed to a vehicle body, an axle bearing torotatably support the reducer housing with respect to the fixed member,and a lubricant oil circulating mechanism to circulate a lubricant oilbetween the reducing mechanism and the axle bearing.

The sealed amount of the lubricant oil can be reduced by circulating thelubricant oil in the reducer housing as described above. As a result,the heat generation and torque loss can be reduced in the reducingmechanism.

Preferably, the lubricant oil circulating mechanism circulates thelubricant oil by use of centrifugal force generated with the rotation ofthe input side rotation member. Thus, the device can be compact in size,as compared with a case where a circulation device is provided outside.

As one embodiment, the lubricant oil circulating mechanism includes alubricant oil path radially penetrating an inside of the fixed member toreturn the lubricant oil from a radial outer side to a radial innerside.

Preferably, the axle bearing is a tapered roller bearing including aninner ring fixed to an outer diameter surface of the fixed member, anouter ring fixed to an inner diameter surface of the reducer housing,and a plurality of tapered rollers arranged between the inner ring andthe outer ring. In addition, a seal member to seal the reducer housingis arranged between the reducer housing and the fixed member so as to beopposed to a large diameter side end of the tapered roller. An openingpart of the lubricant oil path on the radial outer side is providedbetween the tapered roller bearing and the seal member. The lubricantoil in the tapered roller bearing is discharged from the large diameterside end due to the centrifugal force. Thus, the opening part of thelubricant oil path on the radial outer side is preferably provided in aposition adjacent to the large diameter side end of the axle bearing.

As one embodiment, the seal member has a lip part being slidably incontact with an outer diameter surface of the fixed member, and it isfixed to an inner diameter surface of the reducer housing and integrallyrotates with the reducer housing.

Preferably, the input side rotation member has an eccentric part. Thereducing mechanism includes a revolution member rotatably supported withrespect to the eccentric part, to execute revolution motion around arotation axis of the input side rotation member, a rotation regulationmember to prevent rotation motion of the revolution member, allowing therevolution motion thereof, and a periphery engagement member fixed tothe reducer housing, to rotate the reducer housing at speed reduced withrespect to the input side rotation member by engaging with a peripheryof the revolution member. Thus, an opening part of the lubricant oilpath on the radial inner side is provided in a position opposed to theeccentric part. Since the input side rotation member rotates at highspeed, a large amount of lubricant oil is required in the vicinity ofthe eccentric part. Thus, the opening part of the lubricant oil path onthe radial inner side is preferably provided in a position opposed tothe eccentric part.

Preferably, the reducing mechanism is held in a space sealed with thelubricant oil, and the lubricant oil circulating mechanism is providedwith a lubricant oil holding chamber communicating with the space sealedwith the lubricant oil in such a manner that the lubricant oil can bemoved between it and the space.

In the above configuration, the lubricant oil is moved between the spaceand the lubricant oil holding chamber according to a change in oilsurface height in the space sealed with the lubricant oil. As a result,a change in oil surface height can be small between a stopped time andoperated time of the reducing mechanism.

Preferably, the lubricant oil holding chamber is arranged in the reducerhousing. The space and the lubricant oil holding chamber are connectedthrough a vent hole to uniform their internal pressures and a lubricantoil passage to uniform their oil surface heights. Thus, the oil surfaceheight can be adjusted with a simple configuration.

Preferably, the drive unit includes a detecting means for detecting astate of the lubricant oil sealed in the space, and a lubricant oilmoving means for moving the lubricant oil between the space sealed withthe lubricant oil and the lubricant oil holding chamber, based on adetected result of the detecting means.

Preferably, the lubricant oil moving means is a pressure adjustmentdevice to increase a pressure in the lubricant oil holding chamber underthe condition that the detected result of the detecting means exceeds athreshold value, and decrease the pressure in the lubricant oil holdingchamber under the condition that the detected result of the detectingmeans falls below the threshold value. Thus, the appropriate thresholdvalue can be selected based on usage circumstances of the railwayvehicle drive unit.

As one embodiment, the lubricant oil holding chamber has a piston toseparate its inside into a first region isolated from the space sealedwith the lubricant oil, and a second region communicating with the spacesealed with the lubricant oil. Thus, the pressure adjustment deviceincreases or decreases the pressure in the lubricant oil holding chamberby moving the piston.

Preferably, the detecting means is a temperature sensor to detect atemperature of the lubricant oil sealed in the space. The temperature ofthe lubricant oil rises in the operated time of the reducing mechanism.Therefore, when the temperature of the lubricant oil exceeds a constantvalue, the lubricant oil is supplied from the lubricant oil holdingchamber to the space sealed with the lubricant oil, so that the oilsurface height can be adjusted, and the temperature is prevented fromrising.

Preferably, the detecting means is a rotation sensor to detect rotationspeed of the input side rotation member. The centrifugal force appliedto the lubricant oil depends on the rotation speed of the input siderotation member. Therefore, when the rotation speed of the input siderotation member exceeds a constant value, the lubricant oil is suppliedfrom the lubricant oil holding chamber to the space sealed with thelubricant oil, so that the oil surface height can be adjusted.

Preferably, the lubricant oil holding chamber is provided outside thereducer housing. Thus, a degree of freedom in size of the lubricant oilholding chamber can increase.

Preferably, the lubricant oil holding chamber is provided with a filterdevice to filter the internal lubricant oil. Thus, the lubricationperformance of the railway vehicle drive unit can be maintained for along period of time.

In addition, it is preferable that the reducing mechanism is held in aspace sealed with the lubricant oil, and the lubricant oil circulatingmechanism includes a lubricant oil transferring mechanism to transferthe lubricant oil from a bottom region to an upper region in the space,by use of at least one rotation of the reducer housing and the inputside rotation member.

In the above configuration, since the lubricant oil can be activelysupplied to the upper region of the space sealed with the lubricant oilin the reducer housing, the railway vehicle drive unit can be superiorin lubrication performance.

As one embodiment, the lubricant oil transferring mechanism transfersthe lubricant oil from the bottom region to the upper region in thespace sealed with the lubricant oil, by use of the rotation of the inputside rotation member.

Preferably, the drive unit further includes a fixed member arranged inthe reducer housing, and connected and fixed to the vehicle body. Thefixed member internally includes the lubricant oil transferringmechanism, a lubricant oil supply path extending from the lubricant oiltransferring mechanism toward the bottom region in the space sealed withthe lubricant oil, to supply the lubricant oil to the lubricant oiltransferring mechanism, and a lubricant oil discharge path extendingfrom the lubricant oil transferring mechanism toward the upper region inthe space sealed with the lubricant oil, to discharge the lubricant oilfrom the lubricant oil transferring mechanism.

Preferably, the lubricant oil transferring mechanism includes a firstpump to pump up the lubricant oil in response to a positive rotation ofthe input side rotation member, and a second pump to pump up thelubricant oil in response to a negative rotation of the input siderotation member. Thus, the lubricant oil can be pumped when a railwayvehicle goes ahead and goes back.

More specifically, the first pump includes a first drive gear havingteeth around its outer diameter surface, and integrally rotating withthe input side rotation member, and a first driven gear having teethmeshing with the first drive gear, around its inner diameter surface,and being rotatably supported by the fixed member, and rotating around apoint shifted from a rotation center of the first drive gear to onehorizontal direction. The second pump includes a second drive gearhaving teeth around its outer diameter surface and integrally rotatingwith the input side rotation member at a position different from that ofthe first pump, and a second driven gear having teeth meshing with thesecond drive gear, around its inner diameter surface, and beingrotatably supported by the fixed member, and rotating around a pointshifted from a rotation center of the second drive gear to the otherhorizontal direction.

Alternatively, the first pump is composed of a drive gear having teetharound its outer diameter surface and integrally rotating with the inputside rotation member, and a first driven gear having teeth meshing withthe drive gear, around its outer diameter surface, and being rotatablyarranged on one side of the drive gear in a horizontal direction. Thesecond pump is composed of the drive gear, and a second driven gearhaving teeth meshing with the drive gear, around its outer diametersurface, and being rotatable arranged on the other side of the drivegear in the horizontal direction.

As another embodiment, the input side rotation member has an eccentricpart. The reducing mechanism includes a revolution member rotatablysupported with respect to the eccentric part, to execute revolutionmotion around a rotation axis of the input side rotation member, aplurality of rotation regulation members to prevent rotation motion ofthe revolution member, allowing the revolution motion thereof, aperiphery engagement member fixed to the reducer housing, to rotate thereducer housing at speed reduced with respect to the input side rotationmember by engaging with a periphery of the revolution member, and acounterweight fitted and fixed to the input side rotation member with aphase so as to offset unbalance inertia coupling due to eccentricmotion. The lubricant oil transferring mechanism is provided in thecounterweight.

More specifically, the counterweight includes a large diameterfun-shaped part, and a small diameter fun-shaped part having a radiussmaller than that of the large diameter fun-shaped part and connected tothe large diameter fun-shaped part in such as manner that their chordsare in contact with each other. The lubricant oil transferring mechanismhas an opening part in the chord of the large diameter fun-shaped part,and includes a circumferential oil path circumferentially extending inthe large diameter fun-shaped part, and a radial oil path extending fromthe circumferential oil path toward an outer diameter surface of thelarge diameter fun-shaped part.

Alternatively, the counterweight includes a large diameter fun-shapedpart, and a small diameter fun-shaped part having a radius smaller thanthat of the large diameter fun-shaped part and connected to the largediameter fun-shaped part in such as manner that their chords are incontact with each other. The lubricant oil transferring mechanism is afin projecting from an end face of the large diameter fun-shaped part ina thickness direction.

In the above configuration also, the large diameter fun-shaped part ofthe counterweight holds the lubricant oil when the lubricant oil in thereducer housing passes through the bottom region of the space sealedwith the lubricant oil, and discharges it in the upper region, so thatthe lubricant oil can be actively supplied to the upper region.

Further preferably, the reducing mechanism has a plurality of thecounterweights arranged in such a manner that phases of the largediameter fun-shaped parts differ from each other. Thus, the lubricantoil can be stably transferred.

As another embodiment, the lubricant oil transferring mechanismtransfers the lubricant oil from the bottom region to the upper regionin the space sealed with the lubricant oil, by use of the rotation ofthe reducer housing.

Preferably, the lubricant oil transferring mechanism is composed ofconcavo-convex parts formed in surfaces of the reducer housing, and amember rotating with the rotation of the reducer housing. As oneembodiment, the concavo-convex part is composed of projectionsprojecting from an inner diameter surface of the reducer housing andextending in a direction intersecting with a rotation direction of thereducer housing.

Preferably, the projections are provided in a plurality positioned inthe inner diameter surface of the reducer housing, at regular intervals.As a result, the lubricant oil can be stably transferred.

Preferably, a wall surfaces of the projection opposed to acircumferential direction of the reducer housing is in contact with atangent line of the inner diameter surface of the reducer housing, at anacute angle. As one embodiment, a cross-sectional shape of theprojection perpendicular to a rotation axis of the reducer housing is anisosceles trapezoid having a long side and a short side parallel to eachother, and the short side is arranged so as to be in contact with aninner diameter surface of the reducer housing. As a result, an abilityto hold the lubricant oil can be further improved.

Further preferably, the projection is formed in an inner diametersurface of an annular fixed in the inner diameter surface of the reducerhousing. Thus, a structure can be simple as compared with the case wherethe projection is directly formed in the inner diameter surface of thereducer housing.

As another embodiment, the drive unit further includes a fixed memberarranged in the reducer housing, and connected and fixed to the vehiclebody, and an axle bearing including an inner ring fixed to an outerdiameter surface of the fixed member, an outer ring fixed to an innerdiameter surface of the reducer housing, a plurality of rolling bodiesarranged between the inner ring and the outer ring, and a retainerretaining an interval of the adjacent rolling bodies, and rotatablysupporting the reducer housing with respect to the fixed member. Theconcavo-convex part is provided in at least one of the outer ring, therolling body, and the retainer. The concavo-convex part is provided inat least one of the outer ring, the rolling body, and the retainer.

As further another embodiment, the drive unit further includes a fixedmember arranged in the reducer housing, and connected and fixed to thevehicle body, and an annular seal member fixed to an inner diametersurface of the reducer housing, to seal a space between the reducerhousing and the fixed member. The lubricant oil transferring mechanismis a weir expanding from the seal member to a direction intersectingwith a rotation direction of the reducer housing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing a railway vehicle wheel drive device accordingto one embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1.

FIG. 3 is an enlarged view of a periphery of an eccentric part in FIG.1.

FIG. 4 is a view showing a railway vehicle wheel drive device accordingto a second embodiment of the present invention.

FIG. 5 is a view showing a variation of the railway vehicle wheel drivedevice according to the second embodiment of the present invention.

FIG. 6 is a view showing a railway vehicle wheel drive device accordingto a third embodiment of the present invention.

FIG. 7 is a cross-sectional view taken along a line VII-VII in FIG. 6.

FIG. 8 is an enlarged view of a periphery of an eccentric part in FIG.6.

FIG. 9 is an enlarged view of a periphery of a both-sided inner pin.

FIG. 10 is an enlarged view of a periphery of a cantilevered (one-sided)inner pin.

FIG. 11 is one example of a lubricant oil transferring mechanism.

FIG. 12 is another example of a lubricant oil transferring mechanism.

FIG. 13 is still another example of a lubricant oil transferringmechanism.

FIG. 14 is a view showing a counterweight provided with a lubricant oiltransferring mechanism.

FIG. 15 is a view showing a railway vehicle wheel drive device accordingto another embodiment of the present invention.

FIG. 16 is a cross-sectional view taken along a line XVI-XVI in FIG. 15.

FIG. 17 is a view showing a first axle bearing.

FIG. 18 is a front view of a seal member.

BEST MODE FOR CARRYING OUT THE INVENTION (1) First Embodiment

A description will be made of a railway vehicle drive unit 12 accordingto one embodiment of the present invention and a railway vehicle wheeldrive device 10 including the railway vehicle drive unit 12, withreference to FIGS. 1 to 3. In addition, FIG. 1 is a schematiccross-sectional view of the railway vehicle wheel drive device 10, FIG.2 is a cross-sectional view taken along a line II-II in FIG. 1, and FIG.3 is an enlarged view showing a periphery of eccentric parts 16 a and 16b.

First, referring to FIG. 1, the railway vehicle wheel drive device 10 iscomposed of a railway vehicle wheel 11 (hereinafter, referred to as “thewheel 11”) and the drive unit 12 (hereinafter, referred to as “therailway vehicle drive unit 12”) held on an inner diameter surface of thewheel 11 to reduce rotation speed of a drive source (not shown) andtransmit it to the wheel 11, and arranged in a lower part of a railwayvehicle body (not shown).

The railway vehicle drive unit 12 is mainly composed of a reducerhousing 13, an input side rotation member 14, a reducing mechanism 15, acarrier 23 serving as a fixed member, and first and second axle bearings24 and 25.

The reducer housing 13 is held on the inner diameter surface of thewheel 11, and holds the reducing mechanism 15 internally. In addition,the reducing mechanism 15 is composed of an eccentric member 16, curvedplates 17 and 18 serving as revolution members, a plurality of innerpins 19 serving as rotation regulation members, a plurality of outerpins 20 serving as periphery engagement members, and members associatedwith the above components, and reduces rotation speed of the input siderotation member 14 and transmits it to the reducer housing 13.

In addition, the first and second axle bearings 24 and 25 are arrangedbetween an inner diameter surface of the reducer housing 13 and an outerdiameter surface of the carrier 23. The reducer housing 13 is rotatablewith respect to the carrier 23, and also functions as an output siderotation member (axle) integrally rotating with the wheel 11.

The first axle bearing 24 is a tapered roller bearing including an innerring 24 a fixed to the outer diameter surface of the carrier 23, anouter ring 24 b fixed to the inner diameter surface of the reducerhousing 13, a plurality of tapered rollers 24 c arranged between theinner ring 24 a and the outer ring 24 b, a retainer 24 d retaining aninterval of the adjacent tapered rollers 24 c. Since the second rollingbearing 25 has the same configuration, its description is notreiterated. When the tapered roller bearing having high load capacity isused as the first and second axle bearings 24 and 25, a radial load andan axial load applied to the wheel 11 can be appropriately supported.

In addition, the first axle bearing 24 and the second axle bearing 25rotatably support the reducer housing 13 with respect to the carrier 23on one axial side (right side in FIG. 1) of a fit position (morespecifically, “a fit width center of the wheel 11” shown by a dashedline in FIG. 1) of the wheel 11 and on the other axial side (left sidein FIG. 1) of the fit position thereof, respectively. According to thisembodiment, distances (offsets) of the first axle bearing 24 and thesecond axle bearing 25 from the fit width center of the wheel 11 are setto be equal to each other.

Furthermore, the first and second axle bearings 24 and 25 are arrangedsuch that their small diameter side ends are opposed to each other(back-to-back coupling). Thus, a moment load applied to the wheel 11 canbe appropriately supported.

In addition, seal members 26 and 27 to seal a lubricant oil in thereducer housing 13 are provided at both axial ends of the reducerhousing 13. The seal members 26 and 27 each have lip parts being insliding contact with the outer diameter surface of the carrier 23, andare fixed to the inner diameter surface of the reducer housing 13, andintegrally rotate with the reducer housing 13.

The input side rotation member 14 is connected to the drive source (suchas a motor), and rotates with the rotation of the drive source. Inaddition, its both sides are supported by rolling bearings 28 a and 28 bon both sides of the curved plates 17 and 18, and rotatably held withrespect to the carrier 23. In addition, according to this embodiment, acylindrical roller bearing is used as each of the rolling bearings 28 aand 28 b. In addition, a seal member 29 to seal the lubricant oil in thereducer housing 13 is arranged on the outer side (right side in FIG. 1)of the rolling bearing 28 a.

The eccentric member 16 has the first and second eccentric parts 16 aand 16 b, and is fitted and fixed to the input side rotation member 14.The first and second eccentric parts 16 a and 16 b are arranged so as tooffset the centrifugal force due to eccentric motion to each other, thatis, their phases are shifted by 180°. Consequently, the first and secondeccentric parts 16 a and 16 b also function as balance adjustingmechanisms to absorb unbalance load generated due to the eccentricmotion.

The curved plate 17 is supported by a rolling bearing 30 so as to berelatively rotatable with respect to the first eccentric part 16 a, andexecutes revolution motion around a rotation axis of the input siderotation member 14. In addition, referring to FIG. 2, the curved plate17 has first and second through holes 17 a and 17 b penetrating in athickness direction, and a plurality of waveforms 17 c composed of atrochoid-based curve such as epitrochoid along its periphery.

The first through hole 17 a is formed in the center of the curved plate17, and receives the first eccentric part 16 a and the rolling bearing30. The second through holes 17 b are circumferentially provided arounda rotation axis of the curved plate 17 at regular intervals, and receivethe inner pins 19 held by the carrier 23. The waveforms 17 c engage withthe outer pins 20 held by the reducer housing 13, and transmit therotation of the curved plate 17 to the reducer housing 13. In addition,the curved plate 18 has the same configuration, and is rotatablysupported by a rolling bearing 31 with respect to the second eccentricpart 16 b.

The rolling bearing 30 is a cylindrical roller bearing provided with aninner ring member 30 a fitted to an outer diameter surface of theeccentric part 16 a and having an inner side track surface on its outerdiameter surface, an outer side track surface directly formed on theinner diameter surface of the through hole 17 a of the curved plate 17,a plurality of cylindrical rollers 30 b arranged between the inner sidetrack surface and the outer side track surface, and a retainer 30 cretaining an interval of the adjacent cylindrical rollers 30 b. Sincethe rolling bearing 31 has the same configuration, its description isnot reiterated.

In addition, when it is assumed that a center point of the two curvedplates 17 and 18 is G, the center point G coincides with a gravitycenter position of the wheel 11, but the center point G and the wheelgravity center position are preferably offset in order to minimize themoment load applied from the wheel 11 to the railway vehicle drive unit12. Thus, the components (such as the curved plates 17 and 18, the innerpin 19, and outer pin 20) are inclined to prevent an excessive load frombeing generated in a contact part. As a result, the railway vehicledrive unit 12 smoothly rotates, and its durability is improved.

In addition, a circumscribed ring 34 which is circumscribed on theplurality of inner pins 19 is arranged between the two curved plates 17and 18. Thus, an axial motion amount of each of the curved plates 17 and18 is regulated. In addition, since the curved plates 17 and 18 aresliding contact with the circumscribed ring 34, it is preferable thattheir wall surfaces to be in contact with each other are subjected to agrinding treatment. In addition, a function of the circumscribed ring 34may be replaced with an inscribed ring inscribed on the plurality ofinner pins 19, or an inscribed ring inscribed on the plurality of outerpins 20.

The inner pins 19 are circumferentially provided around the rotationaxis of the input side rotation member 14 at regular intervals. Some ofthe plurality of inner pins 19 are roughly in the shape of a columnhaving a large diameter part in the center and a small diameter parthaving a diameter relatively smaller than that of the large diameterpart, at each end. Thus, the small diameter part is held by the carrier23, and the large diameter part is positioned in the second throughholes 17 b and 18 b of the curved plates 17 and 18. In addition, an endface of the large diameter part abuts on a wall surface of the carrier23 to function as a reference surface to position the inner pin 19. Inaddition, the other inner pins 19 are in the shape of a simple columnhaving the same diameter in a longitudinal direction.

Furthermore, an inner pin collar 19 a is attached to a position (largediameter part) which abuts on inner wall surfaces of the second throughholes 17 b and 18 b of the curved plates 17 and 18. Thus, frictionalresistance between the curved plates 17 and 18 and the inner pin 19 canbe reduced. In addition, the inner pin collar 19 a according to thisembodiment is a sliding bearing.

In addition, diameters of the second through holes 17 b and 18 b are setto be larger by a predetermined amount than a diameter (a maximum outerdiameter including the inner pin collar 19 a) of the inner pin 19. Thus,while the curved plates 17 and 18 try to rotate with the rotation of theinput side rotation member 14, the inner pin 19 functions as therotation regulation member to stop rotation motion of the curved plates,allowing the revolution motion thereof.

The outer pins 20 are circumferentially provided around the rotationaxis of the input side rotation member 14 at regular intervals. A centerpart of the outer pin 20 is held by the reducer housing, and both endsthereof abut on the axle bearings 24 and 25 and fixed thereto. Thus, theouter pin 20 engages with the waveforms 17 c and 18 c of the curvedplates 17 and 18 to rotate the reducer housing 13 at speed reduced withrespect to the input side rotation member 14.

Furthermore, an outer pin collar 20 a is attached to a position whichabuts on the waveforms 17 c and 18 c of the curved plates 17 and 18.Thus, frictional resistance between the curved plates 17 and 18 and theouter pin 20 can be reduced. In addition, the outer pin collar 20 aaccording to this embodiment is a sliding bearing.

A counterweight 21 has a through hole to receive the input side rotationmember 14, at a position other than its gravity center, and fitted andfixed to the input side rotation member 14 with its phase shifted so asto offset unbalance inertia couple due to the eccentric motion of theeccentric part 16 a, that it, shifted by 180° from that of the eccentricpart 16 a. Consequently, the counterweight 21 functions as a balanceadjusting mechanism to absorb an unbalance load generated due to theeccentric motion of the eccentric part 16 a. In addition, acounterweight 22 has the same configuration, and is fitted and fixed tothe input side rotation member 14 with its phase shifted to offsetunbalance inertia couple due to eccentric motion of the eccentric part16 b.

Referring to FIG. 3, regarding the right side of the center point G ofthe two curved plates 17 and 18, a relationship that L₁×m₁×ε₁=L₂×m₂×ε₂is satisfied wherein L₁ represents a distance between the center point Gand a center of the curved plate 17, m₁ represents a sum of the mass ofthe curved plate 17, the rolling bearing 30, and the eccentric part 16a, ε₁ represents an eccentric amount of the gravity center of the curvedplate 17 from the rotation axis, L₂ represents a distance between thecenter point G and the counterweight 21, m₂ represents the mass of thecounterweight 21, and ε₂ represents an eccentric amount of the gravitycenter of the counterweight 21 from the rotation axis In addition, thesame relationship is satisfied between the curved plate 18 and thecounterweight 22 on the left side of the center point G in FIG. 3.

The carrier 23 is connected and fixed to the railway vehicle body, andholds the inner pin 19 in wall surfaces opposed to the curved plates 17and 18, and rotatably supports each of the reducer housing 13 with thefirst and second axle bearings 24 and 25 fitted and fixed to its outerdiameter surface, and the input side rotation member 14 with the rollingbearings 28 a and 28 b fitted and fixed to its inner diameter surface.

In addition, the carrier 23 is provided with a lubricant oil circulatingmechanism to circulate the lubricant oil between the reducing mechanism15 and the axle bearings 24 and 25. This lubricant oil circulatingmechanism circulates the lubricant oil by use of the centrifugal forcegenerated due to the rotation of the input side rotation member 14. Morespecifically, a plurality of lubricant oil paths 32 and 33 are formed soas to penetrate the inside of the carrier 23 in a diameter direction toreturn the lubricant oil from the radial outer side to the radial innerside.

An opening part of the lubricant oil path 32 on the radial, outer sideis provided between a large diameter side end of the first axle bearing24 and the seal member 26. Similarly, an opening part of the lubricantoil path 33 on the radial outer side is provided between a largediameter side end of the second axle bearing 25 and the seal member 27.The lubricant oil in the tapered roller bearings 24 and 25 is dischargedfrom the large diameter side end by the centrifugal force. Thus, it ispreferable that the opening parts of the lubricant oil paths 32 and 33on the radial outer side are provided in positions adjacent to the largediameter side ends of the first and second axle bearings 24 and 25,respectively.

Meanwhile, an opening part of the lubricant oil path 32 on the radialinner side is provided in a position opposed to the eccentric part 16 a.Similarly, an opening part of the lubricant oil path 32 on the radialinner side is provided in a position opposed to the eccentric part 16 b.Since the input side rotation member 14 rotates at high speed, a lot oflubricant oil is needed in the vicinity of the eccentric parts 16 a and16 b, or more specifically, in the rolling bearings 30 and 31. Thus, itis preferable that the opening parts of the lubricant oil paths 32 and33 on the radial inner side are provided in the positions opposed to theeccentric parts 16 a and 16 b, respectively.

A detailed description will be made of an operating principle of therailway vehicle drive unit 12 having the above configuration.

First, the input side rotation member 14 and the eccentric member 16integrally rotate with the rotation of the drive source. At this time,while the curved plates 17 and 18 also try to rotate, their rotationmotion is stopped by the inner pins 19 passing through the secondthrough holes 17 b and 18 b, so that they only execute the revolutionmotion. That is, the curved plates 17 and 18 shift in parallel on thecircumferential track around the rotation axis of the input siderotation member 14.

When the curved plates 17 and 18 execute the revolution motion, thewaveforms 17 c and 18 c engage with the outer pins 20, and the reducerhousing 13 and the wheel 11 integrally rotate in the same direction asthat of the input side rotation member 14. At this time, the rotationspeed transmitted from the curved plates 17 and 18 to the reducerhousing 13 has been reduced and torque is high.

More specifically, a reduction ratio of the railway vehicle drive unit12 is calculated by a formula Z_(B)/(Z_(A)−Z_(B)) wherein Z_(A)represents the number of the outer pins 20, and Z_(B) represents thenumber of the waveforms of the curved plates 17 and 18, and a speedratio in this embodiment shown in FIG. 1 is calculated by a formula1/(n+1) wherein n represents the reduction ratio. Since Z_(A)=24 andZ_(B)=22 in the embodiment shown in FIG. 2, the reduction ratio is 11,and the speed ratio is 1/12. Therefore, even when a low-torquehigh-rotation type drive source is used, the torque required for thewheel 11 can be transmitted.

Thus, by employing the reducing mechanism 15 capable of obtaining thehigh reduction ratio without needing a multistage configuration, therailway vehicle drive unit 12 can be compact in size and implement thehigh reduction ratio. In addition, by providing the collars 19 a and 20a for the inner pin 19 and outer pin 20, respectively in the positionswhich abut on the curved plates 17 and 18, the frictional resistance inthe contact parts is reduced. As a result, transmission efficiency isimproved in the railway vehicle drive unit 12.

Next, a detailed description will be made of a flow of the lubricant oilin the railway vehicle drive unit 12 having the above configuration.

First, the lubricant oil is previously sealed in the reducer housing 13.The lubricant oil is carried to the radial outer side by the centrifugalforce generated due to the rotation of the input side rotation member14. At this time, it is supplied to the rolling bearings 28 a, 28 b, 30,and 31, to between the curved plates 17, 18, and the rolling bearings30, 31, between the curved plates 17, 18, and the inner pin 19, betweenthe inner pin 19 and the inner pin collar 19 a, between the curvedplates 17, 18, and the circumscribed ring 34, between the curved plates17, 18, and the outer pin 20, and between the outer pin 20 and the outerpin collar 20 a.

Furthermore, the lubricant oil is discharged to the large diameter sideends of the first and second axle bearings 24 and 25 from the smalldiameter side ends through the inside of the bearings. Thus, thelubricant oil reaches spaces sandwiched between the first and secondaxle bearings 24 and 25, and the seal members 26 and 27, respectivelyand returns to the periphery of the input side rotation member 14through the lubricant oil paths 32 and 33.

Thus, since the lubricant oil is circulated in the railway vehicle driveunit 12, the amount of the sealed lubricant oil can be small. As aresult, heat generation and torque loss are reduced in the railwayvehicle drive unit 12, and the high-speed rotation part (the peripheryof the eccentric part 16) can be surely lubricated. In addition, bycirculating the lubricant oil by use of the centrifugal force generateddue to the rotation of the input side rotation member 14, the unit canbe compact in size as compared with the case where a circulation deviceis provided outside.

In addition, while the two curved plates 17 and 18 of the reducing partB are provided with their phases shifted by 180° in the aboveembodiment, the number of the curved plates may be optionally set, andwhen three curved plates are provided, their phases are shifted by 120°,for example.

In addition, while the eccentric member 16 having the eccentric parts 16a and 16 b is fitted and fixed to the input side rotation member 14 inthe above embodiment, as another example, the eccentric parts 16 a and16 b may be directly formed on the outer diameter surface of the inputside rotation member 14.

Furthermore, the rolling bearings 24, 25, 28 a, 28 b, 30, and 31 in theabove embodiment are not limited to the configurations shown in FIG. 1,and various kinds of bearings can be used such as a sliding bearing,cylindrical roller bearing, tapered roller bearing, needle rollerbearing, self-aligning roller bearing, deep groove ball bearing, angularball bearing, three point contact ball bearing, or four point contactball bearing, regardless of whether the sliding bearing or the rollingbearing, regardless of whether a rolling body is the roller or ball, andregardless of whether a double row or single row.

In addition, while the collars 19 a and 19 b are the sliding bearings inthe above embodiment, the rolling bearing may be used instead. In thiscase, it is preferable to use the needle roller with a view to reducinga size in a thickness direction.

Further, any kind of reducing mechanism can be used in place of theabove described reducing mechanism 15 for the railway vehicle wheeldrive device 10.

(2) Second Embodiment

Next, a second embodiment of the present invention will be described.FIG. 4 is a view showing a configuration of a railway vehicle wheeldrive device according to the second embodiment. Referring to FIG. 4,according to this embodiment, a railway vehicle drive unit 12 iscomposed of a reducer housing 13, an input side rotation member 14, areducing mechanism 15, a carrier 23 as a fixed member, and first andsecond axle bearings 24 and 25, which is the same as the aboveembodiment.

However, this embodiment is different from the above embodiment in thata lubricant oil holding chamber 35 is provided in the carrier 23.Therefore, a part different from that of the above embodiment will bedescribed in detail, and the same part has the same reference, and itsdescription is not reiterated.

The reducer housing 13 has a space sealed with a lubricant oil, and isheld on an inner diameter surface of a wheel 11. The space sealed withthe lubricant oil means a region surrounded by the reducer housing 13,the carrier 23, and seal members 26 and 27. In addition, it internallyholds the reducing mechanism 15.

The reducing mechanism 15 is composed of an eccentric member 16, curvedplates 17 and 18 serving as revolution members, a plurality of innerpins 19 serving as rotation regulation members, a plurality of outerpins 20 serving as periphery engagement members, and members associatedwith the above components, and reduces rotation speed of the input siderotation member 14 and transmits it to the reducer housing 13.

In addition, the reducing mechanism 15 is arranged in the space sealedwith the lubricant oil with at least one part thereof soaked in thelubricant oil. More specifically, the lubricant oil is sealed such thatan oil surface height is at a position of a line m in FIG. 4 under thecondition that the reducing mechanism 15 is stopped.

The lubricant oil holding chamber 35 is arranged in the carrier 23, andcommunicates with the space sealed with the lubricant oil so that thelubricant oil can be moved between them. More specifically, the spacesealed with the lubricant oil and the lubricant oil holding chamber 35are connected through a vent hole 35 a provided to uniform theirinternal pressures, and a lubricant oil path 35 b provided to uniformtheir oil surface heights. Thus, the oil surface height in the lubricantoil holding chamber 35 is at a line m in FIG. 4 under the condition thatthe reducing mechanism 15 is stopped.

In addition, since the lubricant oil sealed in the space spreads alongan inner periphery surface of the reducer housing 13 while the reducingmechanism 15 is operated, the oil surface height becomes lower than theline m in FIG. 4. In this case, the lubricant oil held in the lubricantoil holding chamber 35 is supplied to the space sealed with thelubricant oil through the lubricant oil path 35 b. Meanwhile, when thereducing mechanism 15 is stopped and the oil surface height in the spacesealed with the lubricant oil rises, the lubricant oil is discharged tothe lubricant oil holding chamber 35 through the lubricant oil path 35b. As a result, a variation in oil surface height can be small betweenthe operated time and the stopped time.

In addition, while the lubricant oil holding chamber 35 is arranged inthe carrier 35 in this embodiment, the present invention is not limitedto this, and it may be provided outside the reducer housing 13. When itis arranged in the reducer housing 13, the railway vehicle drive unitcan be compact in size. Meanwhile, when it is arranged outside thereducer housing 13, the lubricant oil holding chamber can be large insize, so that the variation in oil surface height can be further small.

In addition, while the vent hole 35 a and the lubricant oil path 35 bare provided to move the lubricant oil between the space sealed with thelubricant oil and the lubricant oil holding chamber 35 in thisembodiment, the present invention is not limited to this, and anothermethod may be used. FIG. 5 is a view showing a variation of thisembodiment. Referring to FIG. 5, a description will be made of a railwayvehicle wheel drive device 10 and the railway vehicle drive unit 12according to this variation. In addition, the same part as that in FIG.4 has the same reference number and its description is not reiterated.

Referring to FIG. 5, the railway vehicle drive unit 12 is provided witha detecting means 36 for detecting a state of a lubricant oil sealed ina space, and a lubricant oil moving means 37 for moving the lubricantoil between the space sealed with the lubricant oil and a lubricant oilholding chamber 35, based on a detected result of the detecting means36.

The lubricant oil holding chamber 35 in this embodiment is arrangedoutside the reducer housing 13, and communicates with the space sealedwith the lubricant oil through a lubricant oil path 35 b. In addition, apiston 35 c is provided in the lubricant oil holding chamber 35. Thispiston 35 c separates an inside of the lubricant oil holding chamber 35into a first region (an upper region of the piston 35 c) isolated fromthe space sealed with the lubricant oil, and a second region (a lowerregion of the piston 35 c) communicating with the space sealed with thelubricant oil.

The detecting means 36 in this embodiment is a temperature sensor fordetecting a temperature of the lubricant oil sealed in the space, andarranged in a bottom region (position soaked in the lubricant oil allthe time) of the space sealed with the lubricant oil.

The lubricant oil moving means 37 is a pressure adjustment device whichincreases a pressure in the lubricant oil holding chamber under thecondition that the detected result of the temperature sensor exceeds athreshold value, and decreases the pressure in the lubricant oil holdingchamber under the condition that the detected result of the temperaturesensor falls below the threshold value. More specifically, the pressureis increased in the lubricant oil holding chamber 35 by lowering thepiston 35 c, and the pressure is decreased in the lubricant oil holdingchamber 35 by raising the piston 35 c.

In the above configuration, a variation in oil surface height between astopped time and an operated time of the reducing mechanism 15 can besmall. In addition, the embodiment shown in FIG. 1 has a merit that cansimplify the structure. Meanwhile, the threshold value in the embodimentshown in FIG. 4 can be selected according to a usage situation of therailway vehicle drive unit 12.

In addition, the detecting means 36 is not limited to the temperaturesensor, and any kind of sensor may be used as long as it can detect thestate of the lubricant oil sealed in the space directly or indirectly.For example, the detecting means 36 may be a rotation sensor to detectrotation speed of the input side rotation member 14. In this case, thelubricant oil moving means 37 increases a pressure in the lubricant oilholding chamber under the condition that a detected result of therotation sensor exceeds a threshold value, and decreases the pressure inthe lubricant oil holding chamber under the condition that the detectedresult of the rotation sensor falls below the threshold value.

Furthermore, a filter device (not shown) may be provided in thelubricant oil holding chamber 35. The lubrication performance of therailway vehicle drive unit 12 can be maintained for a long period oftime by supplying the lubricant oil filtered by the filter device to thespace sealed with the lubricant oil.

(3) Third Embodiment

Next, a third embodiment of the present invention will be described.FIGS. 6 to 14 are views showing a railway vehicle drive unit accordingto the third embodiment. Referring to these drawings, a description willbe made of a railway vehicle drive unit 112 according to the thirdembodiment and a railway vehicle wheel drive device 110 including therailway vehicle drive unit 112. In addition, FIG. 6 is a schematiccross-sectional view of the railway vehicle wheel drive device 110, FIG.7 is a cross-sectional view taken along a line VII-VII in FIG. 6, FIG. 8is an enlarged view of a periphery of ecentric members 116 a and 116 b,FIG. 9 is an enlarged view of an inner pin 119, FIG. 10 is an enlargedview of an inner pin 120, FIGS. 11 to 13 are views showing pumps as alubricant oil transferring mechanism, and FIG. 14 is a view showing acounterweight 122 provided with a lubricant oil transferring mechanism.

First, referring to FIG. 6, the railway vehicle wheel drive device 110is composed of a railway vehicle wheel 111 (hereinafter referred to asthe “wheel 111”), and the drive unit 112 (hereinafter, referred to as“the railway vehicle drive unit 112”) held on an inner diameter surfaceof the wheel 111 to reduce rotation speed of a drive source (not shown)and transmits it to the wheel 111, and arranged in a lower part of arailway vehicle body (not shown) similar to the above embodiment.

The railway vehicle drive unit 112 is mainly composed of a reducerhousing 113, an input side rotation member 114, a reducing mechanism115, first and second carriers 124 and 125 serving as fixed members,first and second axle bearings 126 and 127, and a lubricant oiltransferring mechanism to transfer a lubricant oil by use of therotation of the input side rotation member 114.

The reducer housing 113 has a space sealed with the lubricant oil and isheld on an inner diameter surface of the wheel 111 similar to the aboveembodiment. The space sealed with the lubricant oil means a regionsurrounded by the reducer housing 113, the first and second carriers 124and 125, and seal members 128 and 129. In addition, it internally holdsthe reducing mechanism 115.

The reducing mechanism 115 is composed of an eccentric member 116,curved plates 117 and 118 serving as revolution members, a plurality ofinner pins 119 and 120 serving as rotation regulation members, aplurality of outer pins 121 serving as periphery engagement members, andmembers associated with the above components, and reduces rotation speedof the input side rotation member 114 and transmits it to the reducerhousing 113.

In addition, the reducing mechanism 115 is arranged in the space sealedwith the lubricant oil with at least one part thereof soaked in thelubricant oil. More specifically, the lubricant oil is sealed such thatan oil surface height is at a position of the line m in FIG. 4 under thecondition that the reducing mechanism 115 is stopped.

In addition, the first and second axle bearings 126 and 127 are arrangedbetween an inner diameter surface of the reducer housing 113 and outerdiameter surfaces of the first and second carriers 124 and 125. Thereducer housing 113 is rotatable with respect to the first and secondcarriers 124 and 125, and also functions as an output side rotationmember (axle) integrally rotating with the wheel 111.

The first axle bearing 126 is a tapered roller bearing including aninner ring 126 a fixed to the outer diameter surface of the firstcarrier 124, an outer ring 126 b fixed to the inner diameter surface ofthe reducer housing 113, a plurality of tapered rollers 126 c arrangedbetween the inner ring 126 a and the outer ring 126 b, a retainer 126 dretaining an interval of the adjacent tapered rollers 126 c. Since thesecond rolling bearing 127 has the same configuration, its descriptionis not reiterated. When the tapered bearing having high load capacity isused as the first and second axle bearings 126 and 127, a radial loadand an axial load applied to the wheel 111 can be appropriatelysupported.

In addition, the first axle bearing 126 and the second axle bearing 127rotatably support the reducer housing 113 with respect to the first andsecond carriers 124 and 125 on one axial side (right side in FIG. 6) ofa fit position (more specifically, “a fit width center of the wheel 111”shown by a dashed line in FIG. 6) of the wheel 111 and on the otheraxial side (left side in FIG. 6) of the fit position thereof,respectively. According to this embodiment, distances (offsets) of thefirst and second axle bearings 126 and 127 from the fit width center ofthe wheel 111 are set to be equal to each other.

Furthermore, the first and second axle bearings 126 and 127 are arrangedsuch that their small diameter side ends are opposed to each other(back-to-back coupling). Thus, a moment load applied to the wheel 111can be appropriately supported.

In addition, seal members 128 and 129 to seal the lubricant oil in thereducer housing 113 are provided at both axial ends of the reducerhousing 113. The seal members 128 and 129 each have lip parts being insliding contact with the outer diameter surfaces of the first and secondcarriers 124 and 125, respectively, and are fixed to the inner diametersurface of the reducer housing 113, and integrally rotate with thereducer housing 13.

The input side rotation member 114 is connected to the drive source(such as a motor), and rotates with the rotation of the drive source. Inaddition, its both sides are supported by rolling bearings 130 a and 130b on both sides of the curved plates 117 and 118, and rotatably heldwith respect to the first and second carriers 124 and 125. In addition,according to this embodiment, a cylindrical roller bearing is used aseach of the rolling bearings 130 a and 130 b. In addition, a seal member131 to seal the lubricant oil in the reducer housing 113 is arranged onthe outer side (right side in FIG. 6) of the rolling bearing 130 a.

The eccentric member 116 has the first and second eccentric parts 116 aand 116 b, and is fitted and fixed to the input side rotation member114. The first and second eccentric parts 116 a and 116 b are arrangedso as to offset the centrifugal force due to eccentric motion to eachother, that is, their phases are shifted by 180°. Consequently, thefirst and second eccentric parts 116 a and 116 b also function as abalance adjusting mechanism to absorb unbalance load generated due tothe eccentric motion.

The curved plate 117 is supported by a rolling bearing 132 so as to berelatively rotatable with respect to the first eccentric part 116 a. Inaddition, it executes revolution motion around a rotation axis of theinput side rotation member 114. Referring to FIG. 7, the curved plate117 has first and second through holes 117 a and 117 b penetrating in athickness direction, a plurality of waveforms 117 c composed of atrochoid-based curve such as epitrochoid along its periphery, an oilpath 117 d internally extending in a radial direction, and a lubricantoil holding space 117 e to temporarily hold the lubricant oil in themiddle of the oil path 117 d.

The first through hole 117 a is formed in the center of the curved plate117, and receives the first eccentric part 116 a and the rolling bearing132. The second through holes 117 b are circumferentially providedaround a rotation axis of the curved plate 117 at regular intervals, andreceive the inner pins 119 and 120 held by the first and second carriers124 and 125. The waveforms 117 c engage with the outer pins 121 held bythe reducer housing 113, and transmit the rotation of the curved plate117 to the reducer housing 113. In addition, the curved plate 118 hasthe same configuration, and is rotatably supported by a rolling bearing133 with respect to the second eccentric part 116 b.

The oil path 117 d extends from the first through hole 117 a to aperipheral surface of the curved plate 117. In addition, while aposition of the oil path 117 d is not limited in particular, it ispreferably provided so as to pass through the second through hole 117 bas shown in FIG. 2. Thus, the lubricant oil can be actively supplied toa contact part between the curved plate 117, and the inner pins 119 and120. In addition, an end of the oil path 117 d on the radial outer sideis preferably formed in a valley part of the waveform 117 c. Thus, thecurved plate 117 and the outer pin 121 are prevented from being damagedwhen they engage with each other.

In addition, since the lubricant oil holding space 117 e branches fromthe oil path 117 d, the lubricant oil can be held in the curved plate117 while a sufficient amount of lubricant oil is supplied, and thelubricant oil held in the lubricant oil holding space 117 e can bedischarged to the oil path 117 d when the supply amount of the lubricantoil decreases. Thus, the lubricant oil can be more stably supplied.

The rolling bearing 132 is a cylindrical roller bearing provided with aninner ring member 132 a fitted to an outer diameter surface of theeccentric part 116 a and having an inner side track surface on its outerdiameter surface, an outer side track surface directly formed on aninner diameter surface of the through hole 117 a of the curved plate117, a plurality of cylindrical rollers 132 b arranged between the innerside track surface and the outer side track surface, and a retainer 132c retaining an interval of the adjacent cylindrical rollers 132 b. Sincethe rolling bearing 133 has the same configuration, its description isnot reiterated.

In addition, when it is assumed that a center point of the two curvedplates 117 and 118 is G, the center point G coincides with a gravitycenter position of the wheel 111, but the center point G and the wheelgravity center position are preferably offset in order to minimize themoment load applied from the wheel 111 to the railway vehicle drive unit112. Thus, the components (such as the curved plates 117 and 118, theinner pins 119 and 120, and the outer pin 121) are inclined to preventan excessive load from being generated in the contact part. As a result,the railway vehicle drive unit 112 smoothly rotates, and its durabilityis improved.

In addition, a circumscribed ring 136 which is circumscribed on theplurality of inner pins 119 and 120 is arranged between the two curvedplates 117 and 118. Thus, an axial motion amount of the curved plates117 and 118 are regulated. In addition, since the curved plates 117 and118 are in sliding contact with the circumscribed ring 136, it ispreferable that their wall surfaces to be in contact with each other aresubjected to a grinding treatment. In addition, a function of thecircumscribed ring 136 may be replaced with an inscribed ring inscribedon the plurality of inner pins 119 and 120, or an inscribed ringinscribed on the plurality of outer pins 121.

The inner pins 119 and 120 are circumferentially provided around therotation axis of the input side rotation member 114 at regularintervals. In addition, inner pin bearings 119 e and 120 e are mountedon positions (such as a large diameter part 119 a in the case of theboth-sided inner pin 119) which abuts on the inner wall surfaces of thesecond through holes 117 b and 118 b of the curved plates 117 and 118,respectively. Thus, frictional resistance between the curved plates 117and 118, and the inner pins 119 and 120 can be reduced. In addition, theinner pin bearings 119 e and 120 e according to this embodiment aresliding bearings.

Referring to FIG. 9, the inner pin 119 includes the large diameter part119 a provided in its axial center, first and second small diameterparts 119 b and 119 c each having a diameter smaller than that of thelarge diameter part 119 a and provided at its axial both ends, and aguide part 119 d provided between the large diameter part 119 a and eachof the first and second small diameter parts 119 b and 119 c. A malescrew is formed in a peripheral surface of each of the first and secondsmall diameter parts 119 b and 119 c. An outer diameter of the guidepart 119 d is set so as to coincide with an inner diameter of holes 124a and 125 a to receive the both-sided inner pin 119, and used toposition the inner pin 119 in the radial direction with respect to thefirst and second carriers 124 and 125.

This inner pin 119 is the both-sided inner pin which is supported atboth ends by the first and second carriers 124 and 125. Morespecifically, the first small diameter part 119 b is directly fixed tothe first carrier 124, and the second small diameter part 119 c is fixedsuch that the second carrier 25 is pressed to an end face of the largediameter part 119 a by a pressing and fixing means (which will bedescribed below).

Referring to FIG. 10, the inner pin 120 is in the shape of a simplecolumn having the same diameter in a whole longitudinal direction, andit is a cantilevered (hereinafter referred as “one-sided”) inner pin inwhich only one axial side end is supported by the first carrier 124.

In addition, the one-sided inner pin 120 is provided with a lubricantoil holding space 120 a formed in its inside, and a through hole 120 bradially extending from the lubricant oil holding space 120 a.Similarly, the inner pin bearing 120 e is provided with a through hole120 f penetrating in the radial direction. In addition, while thepositions of the through holes 120 b and 120 f are not limited inparticular, they are preferably provided so as to be opposed to thespace between the curved plates 117 and 118 as shown in FIG. 10.

The lubricant oil is held in the lubricant oil holding space 120 a, andmainly supplied to between the inner pin 120 and the inner pin bearing120 e, and to the contact part between the inner pin bearing 120 e andthe curved plates 117 and 118. More specifically, the lubricant oil isheld in the lubricant oil holding space 120 e while a sufficient amountof lubricant oil is supplied, and the lubricant oil held in thelubricant oil holding space 120 e is discharged through the throughholes 120 b and 120 f when the supply amount of the lubricant oildecreases. Thus, the lubricant oil can be more stably supplied.

In addition, a porous material (not shown) impregnated with thelubricant oil may be stored in the lubricant oil holding space 120 a. Inthis case, since the lubricant oil comes out gradually through thethrough holes 120 b and 120 f, the lubricant oil can be supplied stablyover a long period of time. In addition, the porous material includessintered metal or foamed grease.

In addition, while the one-sided inner pin 120 is only provided with thelubricant oil holding space 120 a and the through hole 120 b, and theinner pin bearing 120 e is only provided with the through hole 120 f inthe above embodiment, the both-sided inner pin 119 and the inner pinbearing 119 e may be similarly configured. In addition, not only theinner pins 119 and 120, but also the outer pin 121 and an outer pinbearing 121 a may be also similarly configured.

In addition, diameters of the second through holes 117 b and 118 b areset to be larger by a predetermined amount than diameters (maximum outerdiameters including the inner pin bearings 119 e and 120 e) of the innerpins 119 and 120. As a result, while the curved plates 117 and 118 tryto rotate with the rotation of the input side rotation member 114, theinner pin 119 functions as the rotation regulation member to stoprotation motion of the curved plates, while allowing the revolutionmotions thereof.

The outer pins 121 are circumferentially provided around the rotationaxis of the input side rotation member 114 at regular intervals. Acenter part of the outer pin 121 is held by the reducer housing, andboth ends thereof abut on the axle bearings 126 and 127 and fixedthereto. Thus, the outer pin 121 engages with the waveforms 117 c and118 c of the curved plates 117 and 118 to rotate the reducer housing 113at speed reduced with respect to the input side rotation member 114.

Furthermore, the outer pin bearing 121 a is attached to a position whichabuts on the waveforms 117 c and 118 c of the curved plates 117 and 118.Thus, frictional resistance between the curved plates 117 and 118 andthe outer pin 121 can be reduced. In addition, the outer pin bearing 121a according to this embodiment is a sliding bearing.

The counterweight 122 has a through hole to receive the input siderotation member 114, at a position other than its gravity center, andfitted and fixed to the input side rotation member 114 with its phaseshifted so as to offset unbalance inertia couple due to the eccentricmotion of the eccentric part 116 a, that it, shifted by 180° from thatof the eccentric part 116 a. Consequently, the counterweight 122functions as a balance adjusting mechanism to absorb an unbalance loadgenerated due to the eccentric motion of the eccentric part 116 a. Inaddition, a counterweight 123 has the same configuration, and is fittedand fixed to the input side rotation member 114 with its phase shiftedto offset unbalance inertia couple due to eccentric motion of theeccentric part 116 b.

Referring to FIG. 8, regarding the right side of the center point G ofthe two curved plates 117 and 118, a relationship thatL₁₁×m₁₁×ε₁₁=L₁₂×m₁₂×ε₁₂ is satisfied wherein L₁₁ represents a distancebetween the center point G and a center of the curved plate 117, m₁₁represents a sum of the mass of the curved plate 117, the rollingbearing 132, and the eccentric part 116 a, ε₁₁ represents an eccentricamount of the gravity center of the curved plate 117 from the rotationaxis, L₁₂ represents a distance between the center point G and thecounterweight 122, m₁₂ represents the mass of the counterweight 122, andε₁₂ represents an eccentric amount of the gravity center of thecounterweight 122 from the rotation axis. In addition, the samerelationship is satisfied between the curved plate 118 and thecounterweight 123 on the left side of the center point G in FIG. 3.

The first and second carriers 124 and 125 are connected and fixed to therailway vehicle body, and hold the inner pins 119 and 120 in wallsurfaces opposed to the curved plates 117 and 118, and rotatably supporteach of the reducer housing 113 with the first and second axle bearings126 and 127 fitted and fixed to their outer diameter surfaces, and theinput side rotation member 114 with the rolling bearings 130 a and 130 bfitted and fixed to their inner diameter surfaces.

The first carrier 124 has the hole 124 a to receive the first smalldiameter part 119 b of the both-sided inner pin 119, and a hole 124 b toreceive the one axial side end of the one-sided inner pin 120. Inaddition, the hole 124 a is a screw hole in which a female screw isformed on its inner wall surface. Meanwhile, the hole 124 b is a simplehole (in which a screw is not formed).

The second carrier 125 has the hole 125 a to receive the second smalldiameter part 119 c of the both-sided inner pin 119, and a hole 125 b toreceive the other axial side end of the one-sided inner pin 120. Inaddition, a diameter of the through hole 125 a is set to be larger thanthat of the second small diameter part 119 c, and a diameter of the hole125 b is set to be larger than that of the one-sided inner pin 120.

Hereinafter, a description will be made of a method for mounting theinner pins 119 and 120 on the first and second carriers 124 and 125.First, the inner pins 119 and 120 are fixed to the first carrier 124.More specifically, the first small diameter part 119 b of the both-sidedinner pin 119 is screwed with the hole 124 a and fixed thereto, and theone axial side end of the one-sided inner pin 120 is pressed in the hole124 b and fixed thereto.

In addition, the method for fixing the inner pins 119 and 120 to thefirst carrier 124 is not limited to the above example, and as anotherexample, the one side end of the both-sided inner pin 119 may be pressedinto the hole 124 a, while screws are formed in each of the one side endof the one-sided inner pin 120 and the hole 124 b, and they may bescrewed.

Then, the inner pin bearings 119 e and 120 e are mounted on the innerpins 119 and 120, respectively.

Then, the second carrier 125 is mounted in such a manner that the secondsmall diameter part 119 c of the both-sided inner pin 119 is insertedinto the through hole 125 a, and the other axial side end of theone-sided inner pin 120 is inserted into the hole 125 b. At this time,since a gap is provided between the inner pin 119 and 120 and thethrough holes 125 a and 125 b, respectively, some degree of productionerror and mounting error are allowed.

Finally, the both-sided inner pin 119 is fixed by the pressing andfixing means. The pressing and fixing means according to this embodimentis composed of a male screw provided in the second small diameter part119 c and a nut 137 to be screwed with it. That is, when the nut 137 isscrewed with the second small diameter part 119 c, the second carrier125 is pressed toward the large diameter part 119 a, so that theboth-sided inner pin 119 can be strongly fixed to the first and secondcarriers 124 and 125.

At this time, the both-sided inner pin 119 is radially positioned by theguide part 119 d. In addition, while the guide part 119 d is in thecylindrical shape in FIG. 9, the present invention is not limited tothis, and any shape may be employed. For example, when the guide part isin the shape of a cone in which its diameter gradually reduces towardthe end of the both-sided inner pin 119, and opening parts of the holes124 a and 125 a opposed to the both-sided inner pin 119 are formed intoconical surfaces to correspond to the shape of the guide part, thepositioning can be further easily performed.

According to the above embodiment, an assembling property is improved inthe railway vehicle drive unit 112. In addition, with a view toimproving the assembling property and reducing the number of components,the number of the both-sided inner pins 119 is desirably less than thenumber of the one-sided inner pin 120. However, since loads are appliedfrom the curved plates 117 and 118 to the inner pins 119 and 120, it isdesirable that the both-sided inner pins 119 and the one-sided innerpins 120 are arranged at regular intervals, respectively.

The lubricant oil transferring mechanism transfers the lubricant oilfrom a bottom region to an upper region in the above space sealed withthe lubricant oil, by use of the rotation of the input side rotationmember 114. More specifically, it includes a pump 141 arranged in thefirst carrier 124, a lubricant oil supply path 134 extending from thepump 141 toward the bottom region of the space sealed with the lubricantoil, to supply the lubricant oil to the pump 141, and a lubricant oildischarge path 135 extending from the pump 141 toward the upper regionof the space sealed with the lubricant oil, to discharge the lubricantoil from the pump 141.

Referring to FIG. 11, the pump 141 is a cycloidal pump composed of adrive gear 142 having teeth around its outer diameter surface andintegrally rotating with the input side rotation member 114, and adriven gear 143 having teeth around its inner diameter surface,rotatably supported by the first carrier 124, and rotating around apoint c₂ which is shifted from a rotation center c₁ of the drive gear142 in one horizontal direction.

The above pump 141 can discharge the lubricant oil pumped from thebottom region of the space through the lubricant oil supply path 134, tothe upper region through the lubricant oil discharge path 135 when theinput side rotation member 114 rotates in a counterclockwise direction(positive rotation).

Meanwhile, the above pump 141 cannot transfer the lubricant oil when theinput side rotation member 114 rotates in a clockwise direction(negative rotation). Thus, it is preferable to provide a second pumpcapable of transferring the lubricant oil when the input side rotationmember 114 rotates in the clockwise direction, separately from the pump141. More specifically, the pump has the same structure of the pump 141except for having a reversed positional relationship between c₁ and c₂.

Referring to FIG. 12, a pump 151 according to another embodiment iscomposed of a drive gear 152 having teeth around its outer diametersurface and integrally rotating with the input side rotation member 114,and a driven gear 153 having teeth meshing with the drive gear 152around its outer diameter surface, and rotatably arranged on onehorizontal direction of the drive gear 152. In addition, according tothis embodiment, the driven gear 153 is fitted and fixed to a rotationshaft 124 c rotatably mounted on the first carrier 124.

Even when the above pump 151 is used instead of the pump 141 in FIG. 11,the lubricant oil can be transferred when the input side rotation member114 rotates in the counterclockwise direction. In addition, by providinga second pump having the same structure as that of the pump 141 exceptfor having a reversed positional relationship between the drive gear 152and the driven gear 153, the lubricant oil can be transferred when theinput side rotation member 114 rotates in the clockwise direction.

Furthermore, referring to FIG. 13, a pump 161 according to still anotherembodiment is composed of a drive gear 162 having teeth around its outerdiameter surface, and integrally rotating with the input side rotationmember 114, a first driven gear 163 having teeth meshing with the drivegear 162 around its outer diameter surface, and rotatably arranged onehorizontal direction of the drive gear 162, and a second driven gear 164having teeth meshing with the drive gear 162 around its outer diametersurface, and rotatably arranged on the other horizontal side of thedrive gear 162. In addition, according to this embodiment, the drivengears 163 and 164 are fitted and fixed to rotation shafts 124 c and 124d rotatably mounted on the first carrier 124.

According to the above pump 161, when the input side rotation member 114rotates in the counterclockwise direction, the drive gear 162 and thefirst driven gear 163 function as first pumps to transfer the lubricantoil. Meanwhile, when the input side rotation member 114 rotates in theclockwise direction, the drive gear 162 and the second driven gear 164function as second pumps to transfer the lubricant oil. Thus, ascompared with the case where the pump 141 or 151 shown in FIG. 11 orFIG. 12 is arranged at two positions, a space for the pump can be small.

While the pump is used as the lubricant oil transferring mechanism inthe above embodiment, the present invention is not limited to this, andany configuration may be used as long as the lubricant oil istransferred by the use of the rotation of the input side rotation member114. For example, as shown in FIG. 14, the lubricant oil transferringmechanism may be provided in the counterweight 122. Since acounterweight 123 is similarly configured, its description is notreiterated.

Referring to FIG. 14, the counterweight 122 includes a large diameterfan-shaped part 122 a, and a small diameter fan-shaped part 122 b havinga radius smaller than that of the large diameter fan-shaped part 122 a,and connected to the large diameter fan-shaped part 122 a such thattheir chords are in contact with each other.

In addition, the large diameter fan-shaped part 122 a is provided with acircumferential oil path 122 c having an opening part in its chord andcircumferentially extending in the large diameter fan-shaped part 122 a,and a radial oil path 122 d extending from the circumferential oil path122 c toward an outer diameter surface of the large diameter fan-shapedpart 122 a. In addition, a plurality of fins 122 e protruding in athickness direction are provided on an end face of the balance weight122.

An operational principle of the above railway vehicle drive unit 112will be described in detail.

First, the input side rotation member 114 and the eccentric member 116integrally rotate with the rotation of the drive source. At this time,while the curved plates 117 and 118 also try to rotate, their rotationmotion is stopped by the inner pins 119 and 120 passing through thesecond through holes 117 b and 118 b, so that they only execute therevolution motion. That is, the curved plates 117 and 118 shift inparallel on the circumferential track around the rotation axis of theinput side rotation member 114.

When the curved plates 117 and 118 execute the revolution motion, thewaveforms 117 c and 118 c engage with the outer pins 121, the reducerhousing 113 and the wheel 111 integrally rotate in the same direction asthat of the input side rotation member 114. At this time, the rotationspeed transmitted from the curved plates 117 and 118 to the reducerhousing 113 has been reduced and torque is high.

More specifically, a reduction ratio of the railway vehicle drive unit112 is calculated by a formula Z_(B1)/(Z_(A1)−Z_(B1)) wherein Z_(A1)represents the number of the outer pins 121, and Z_(B1) represents thenumber of the waveforms of the curved plates 117 and 118, and a speedratio in this embodiment shown in FIG. 1 is calculated by a formula1/(n1+1) wherein n1 represents the reduction ratio. Since Z_(A1)=24 andZ_(B1)=22 in the embodiment shown in FIG. 2, the reduction ratio is 11,and the speed ratio is 1/12. Therefore, even when a low-torquehigh-rotation type drive source is used, the torque required for thewheel 111 can be transmitted.

Thus, by employing the reducing mechanism 15 capable of obtaining thehigh reduction ratio without needing a multistage configuration, therailway vehicle drive unit 112 can be compact in size and implement thehigh reduction ratio. In addition, by providing the pin bearings 119 eand 120 e and the outer pin bearing 121 a for the inner pins 119 and 120and the outer pin 121, respectively which abut on the curved plates 117and 118, the frictional resistance in the contact part is reduced. As aresult, transmission efficiency is improved in the railway vehicle driveunit 112.

Hereinafter, the flow of the lubricant oil in the above railway vehicledrive unit 112 will be described in detail. First, the lubricant oil issealed in the space sealed with the lubricant oil in the reducer housing113, that is, in the region surrounded by the reducer housing 113, thefirst and second carriers 124 and 125, and the seal members 128 and 129,and an oil surface height is at the position of a line m in FIG. 6 underthe condition that the reducing mechanism 15 is stopped.

When the input side rotation member 114 rotates, the pump 141 serving asthe lubricant oil transferring mechanism discharges the lubricant oilpumped from the bottom region of the space sealed with the lubricant oilthrough the lubricant oil supply path 134, to the upper region throughthe lubricant oil discharge path 135. In addition, the counterweight 122serving as the lubricant oil transferring mechanism rotates and movesbetween the bottom region and the upper region in the space sealed withthe lubricant oil. At this time, in the bottom region, the lubricant oilis stored in the circumferential oil path 122 c and the radial oil path122 d, and in the upper region, the lubricant oil is discharged, and thelubricant oil is propelled upward by the fin 122 e. Thus, the lubricantoil can be supplied to the upper region of the space sealed with thelubricant oil (the region on the upper side of the input side rotationmember 114 in FIG. 6).

The lubricant oil discharged by the lubricant oil transferring mechanismlubricates the components positioned in the upper region, especially,the space between the inner pin 119 and the inner bin bearing 119 e, andthe space between the inner pin bearing 119 e and the curved plates 117and 118 while being returned to the bottom region due to gravity. Inaddition, it is partially held in the lubricant oil holding spaces 117 eand 120 a.

Thus, when the lubricant oil transferring mechanism is configured asdescribed above, the lubricant oil can be actively supplied to the upperregion of the space sealed with the lubricant oil in the reducer housing113, so that the railway vehicle drive unit 112 can be superior inlubrication performance. In addition, all the above-described lubricantoil transferring mechanisms (the pumps 141, 151, and 161, and thecounterweight 122) are not necessarily provided, and the effect of thepresent invention can be provided even with at least one of them.

In addition, the counterweights 122 and 123 having the lubricant oiltransferring mechanism are arranged with their phases shifted by 180° inthe embodiment shown in FIG. 6. Thus, when one large diameter fan-shapedpart is positioned in the bottom region of the space sealed with thelubricant oil in the reducer housing 113, the other large diameterfan-shaped part discharges the lubricant oil in the upper region of thespace sealed with the lubricant oil in the reducer housing 113. As aresult, the lubricant oil can be stably transferred.

(4) Fourth Embodiment

Next, a description will be made of a railway vehicle drive unit 112 aaccording to a fourth embodiment of the present invention, and a railwayvehicle wheel drive device 110 a including the railway vehicle driveunit 112 a. In addition, the same reference is allocated to the samecomponent as that of the second embodiment in the following drawings andits description is not reiterated. FIG. 15 is a schematiccross-sectional view of the railway vehicle wheel drive device 110 a,FIG. 16 is a cross-sectional view taken along a line XI-XI in FIG. 15,and FIG. 17 is a view showing a first axel bearing 126, and FIG. 18 is afront view of a seal member 128.

Referring to FIG. 15, the railway vehicle drive unit 112 a according toanother embodiment is mainly composed of a reducer housing 113, an inputside rotation member 114, a reducing mechanism 115, first and secondcarriers 124 and 125 serving as fixed members, first and second axlebearings 126 and 127, and a lubricant oil transferring mechanism totransfer a lubricant oil by use of the rotation of the reducer housing113.

The lubricant oil transferring mechanism transfers the lubricant oilfrom a bottom region to an upper region of a space sealed with thelubricant oil, that is, a region surrounded by the reducer housing 113,the first and second carriers 124 and 125, and seal members 128 and 129,by the use of the rotation of the reducer housing 113. Morespecifically, it is a mechanism composed of a concavo-convex part formedin a surface of the reducer housing 113, and members rotating with therotation of the reducer housing 113. In addition, “members rotating withthe rotation of the reducer housing 113” correspond to an outer pin 121and an outer pin bearing 121 a, outer rings 126 b and 127 b, taperedrollers 126 c and 127 c, and retainers 126 d and 127 d of the first andsecond axle bearings 126 and 127, and the seal members 128 and 129.

Referring to FIG. 16, a concavo-convex part 113 a is formed in the innerdiameter surface of the reducer housing 113. The concavo-convex part 113a according to this embodiment is a protrusion extending in a directionintersecting with a rotation direction of the reducer housing 113. Inaddition, this concavo-convex part 113 a may be directly formed in theinner diameter surface of the reducer housing 113, or an annular belt(not shown) having the concavo-convex part 113 a in its inner diametersurface may be fixed on the inner diameter surface of the reducerhousing 113.

While the shape of the protrusion is not limited in particular,according to this embodiment, a cross section of the protrusion takenalong a line perpendicular to a rotation axis of the reducer housing 113is in a shape of an isosceles trapezoid having a short side and a longside which are parallel to each other. The protrusion is arranged suchthat the short side is in contact with the inner diameter surface of thereducer housing 113. In other words, a wall surface of the protrusionopposed to the circumferential direction of the reducer housing 113 (thewall surface corresponding to an oblique side of the isoscelestrapezoid) is in contact with a tangent line of the inner diametersurface of the reducer housing 113 at a sharp angle. Thus, an ability tohold the lubricant oil by the protrusion is improved.

In addition, the protrusions are arranged in 12 positions around theinner diameter surface of the reducer housing 113 at intervals of 30°.Thus, by providing the protrusions at regular intervals, the lubricantoil can be stably transferred.

Referring to FIG. 17, concavo-convex parts 126 e are also formed in thefirst axle bearing 126. The concavo-convex parts 126 e according to thisembodiment are provided in an inner diameter surface of the outer ring126 b, an end face of the tapered roller 126 c, and an end face of theretainer 126 d. In addition, since the second axle bearing 127 issimilarly provided, its description is not reiterated.

Referring to FIG. 15, the seal member 128 is provided with a weir 128 aexpanding in a direction intersecting with the rotation direction of thereducer housing 113. This weir 128 a also functions as the lubricant oiltransferring mechanism. Referring to FIG. 18, the weirs 128 a accordingto this embodiment are regularly provided in 8 positions at intervals of45°.

In addition, since the other components constituting the railway vehicledrive unit 112 b are the same as those of the railway vehicle drive unit112 according to the second embodiment, their descriptions are notreiterated.

Here, a detailed description will be made of a flow of the lubricant oilof the railway vehicle drive unit 112 a according to another embodiment.First, the lubricant oil is sealed in a space of the reducer housing113, that is, in the region surrounded by the reducer housing 113, thefirst and second carriers 124 and 125, and the seal members 128 and 129,and an oil surface height is at a position of a line m in FIG. 15 underthe condition that the reducing mechanism 15 is stopped.

When the reducer housing 113 rotates, the lubricant oil transferringmechanism (the concavo-convex parts 113 a and 126 e, and the weir 128)moves between the bottom region and the upper region of the space sealedwith the lubricant oil while rotating in the space. At this time, thelubricant oil is stored in a bottom region, and the lubricant oil isdischarged in an upper region. Thus, the lubricant oil can be suppliedto an upper region (region on the upper side of the input side rotationmember 114 in FIG. 15) in the space sealed with the lubricant oil.

The lubricant oil discharged by the lubricant oil transferring mechanismlubricates the components positioned in the upper region, such as thespace between the inner pin 119 and the inner pin bearing 119 e, and thespace between the inner pin bearing 119 e and the curved plates 117 and118, while being returned to the bottom region due to the gravity. Inaddition, it is partially held in lubricant oil holding spaces 117 e and120 a.

When the lubricant oil transferring mechanism is configured as describedabove, the lubricant oil can be actively supplied to the upper region inthe space sealed with the lubricant oil in the reducer housing 113, sothat the railway vehicle drive unit 112 a can be superior in lubricationperformance. In addition, there is no need to provide all theabove-described lubricant oil transferring mechanisms (theconcavo-convex parts 113 and 126 e, and the weir 128), and the effect ofthe present invention can be provided even with at least one of them.

In addition, while the curved plates 117 and 118 of the reducingmechanism 15 are arranged with their phases shifted by 180° in the aboveembodiment, the number of the curved plates can be optionally set. Forexample, when three curved plates are provided, for example, they arearranged with their phases shifted by 120°.

In addition, while the eccentric member 116 having the eccentric parts116 a and 116 b is fitted and fixed to the input side rotation member114 in the above embodiment, the present invention is not limited tothis, and the eccentric parts 116 a and 116 b may be formed directly onthe outer surface of the input side rotation member 114.

In addition, while the lubricant oil transferring mechanism transfersthe lubricant oil by use of the rotation of the input side rotationmember 114 as one embodiment, and the lubricant oil transferringmechanism transfers the lubricant oil by use of the rotation of thereducer housing 113 as another embodiment, in the third embodiment, thepresent invention is not limited to the above embodiments, and thelubricant oil transferring mechanism may transfer the lubricant oil byuse of both of the rotations of the input side rotation member 114 andthe reducer housing 113. For example, the lubricant oil may betransferred by providing the above-described pump 141 and also providingthe concavo-convex parts 126 e in the first axle bearing 126. Thus, thelubrication performance can be further improved.

In addition, the rolling bearings 126, 127, 130 a, 130 b, 132, and 133in the above embodiments are not limited to the configurations shown inthe drawing, and various kinds of bearings can be used such as a slidingbearing, cylindrical roller bearing, tapered roller bearing, needleroller bearing, self-aligning roller bearing, deep groove ball bearing,angular ball bearing, three point contact ball bearing, or four pointcontact ball bearing, regardless of whether the sliding bearing or therolling bearing, regardless of whether a rolling body is the roller orball, and regardless of whether a double row or single row.

In addition; while the inner pin bearing 119 e and 120 e and the outerpin bearing 121 a in the above embodiment are the sliding bearings, thepresent invention is not limited to this, and a rolling bearing may beemployed. In this case, it is preferable to employ a needle rollerbearing with a view to reducing a size in a thickness direction.

Although the embodiments of the present invention have been describedwith reference to the drawings in the above, the present invention isnot limited to the above-illustrated embodiments. Various kinds ofmodifications and variations may be added to the illustrated embodimentswithin the same or equal scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention can be advantageously applied to a railway vehicledrive unit.

1. A railway vehicle drive unit to rotatably drive a wheel of a railwayvehicle, comprising: a reducer housing held on an inner diameter surfaceof the wheel, and integrally rotating with the wheel; an input siderotation member connected to a drive source; a reducing mechanism toreduce rotation speed of said input side rotation member and transmit itto said reducer housing; a fixed member arranged in said reducerhousing, and connected and fixed to a vehicle body; an axle bearing torotatably support said reducer housing with respect to said fixedmember; and a lubricant oil circulating mechanism to circulate alubricant oil between said reducing mechanism and said axle bearing. 2.The railway vehicle drive unit according to claim 1, wherein saidlubricant oil circulating mechanism circulates the lubricant oil by useof centrifugal force generated with the rotation of said input siderotation member.
 3. The railway vehicle drive unit according to claim 1,wherein said lubricant oil circulating mechanism includes a lubricantoil path radially penetrating an inside of said fixed member to returnthe lubricant oil from a radial outer side to a radial inner side. 4.The railway vehicle drive unit according to claim 3, wherein said axlebearing is a tapered roller bearing including an inner ring fixed to anouter diameter surface of said fixed member, an outer ring fixed to aninner diameter surface of said reducer housing, and a plurality oftapered rollers arranged between said inner ring and said outer ring, aseal member to seal said reducer housing is arranged between saidreducer housing and said fixed member so as to be opposed to a largediameter side end of said tapered roller, and an opening part of saidlubricant oil path on the radial outer side is provided between saidtapered roller bearing and said seal member.
 5. The railway vehicledrive unit according to claim 4, wherein said seal member has a lip partbeing slidably in contact with the outer diameter surface of said fixedmember, and it is fixed to the inner diameter surface of said reducerhousing, and integrally rotates with said reducer housing.
 6. Therailway vehicle drive unit according to claim 3, wherein said input siderotation member has an eccentric part, said reducing mechanism includes:a revolution member rotatably supported with respect to said eccentricpart, to execute revolution motion around a rotation axis of said inputside rotation member; a rotation regulation member to prevent rotationmotion of said revolution member, allowing the revolution motionthereof; and a periphery engagement member fixed to said reducerhousing, to rotate said reducer housing at speed reduced with respect tosaid input side rotation member by engaging with a periphery of saidrevolution member, and an opening part of said lubricant oil path on theradial inner side is provided in a position opposed to said eccentricpart.
 7. The railway vehicle drive unit according to claim 1, whereinsaid reducing mechanism is held in a space sealed with the lubricantoil, and said lubricant oil circulating mechanism is provided with alubricant oil holding chamber communicating with said space sealed withsaid lubricant oil in such a manner that said lubricant oil can be movedbetween it and said space.
 8. The railway vehicle drive unit accordingto claim 7, wherein said lubricant oil holding chamber is arranged insaid reducer housing, and said space and said lubricant oil holdingchamber are connected through a vent hole to uniform their internalpressures and a lubricant oil passage to uniform their oil surfaceheights.
 9. The railway vehicle drive unit according to claim 7, furthercomprising: a detecting means for detecting a state of the lubricant oilsealed in said space; and a lubricant oil moving means for moving thelubricant oil between said space and said lubricant oil holding chamber,based on a detected result of said detecting means.
 10. The railwayvehicle drive unit according to claim 9, wherein said lubricant oilmoving means is a pressure adjustment device to increase a pressure insaid lubricant oil holding chamber under the condition that the detectedresult of said detecting means exceeds a threshold value, and decreasethe pressure in said lubricant oil holding chamber under the conditionthat the detected result of said detecting means falls below thethreshold value.
 11. The railway vehicle drive unit according to claim10, wherein said lubricant oil holding chamber has a piston to separateits inside into a first region isolated from said space, and a secondregion communicating with said space, and said pressure adjustmentdevice increases or decreases the pressure in said lubricant oil holdingchamber by moving said piston.
 12. The railway vehicle drive unitaccording to claim 9, wherein said detecting means is a temperaturesensor to detect a temperature of the lubricant oil sealed in saidspace.
 13. The railway vehicle drive unit according to claim 9, whereinsaid detecting means is a rotation sensor to detect rotation speed ofsaid input side rotation member.
 14. The railway vehicle drive unitaccording to claim 9, wherein said lubricant oil holding chamber isprovided outside said reducer housing.
 15. The railway vehicle driveunit according to claim 7, wherein said lubricant oil holding chamber isprovided with a filter device to filter the internal lubricant oil. 16.The railway vehicle drive unit according to claim 1, wherein saidreducing mechanism is held in a space sealed with the lubricant oil, andsaid lubricant oil circulating mechanism comprises a lubricant oiltransferring mechanism to transfer the lubricant oil from a bottomregion to an upper region in said space, by use of at least one rotationof said reducer housing and said input side rotation member.
 17. Therailway vehicle drive unit according to claim 16, wherein said lubricantoil transferring mechanism transfers the lubricant oil from the bottomregion to the upper region in said space, by use of the rotation of saidinput side rotation member.
 18. The railway vehicle drive unit accordingto claim 17, further comprising a fixed member arranged in said reducerhousing, and connected and fixed to the vehicle body, wherein said fixedmember internally includes: said lubricant oil transferring mechanism; alubricant oil supply path extending from said lubricant oil transferringmechanism toward the bottom region in said space, to supply thelubricant oil to said lubricant oil transferring mechanism, and alubricant oil discharge path extending from said lubricant oiltransferring mechanism toward the upper region in said space, todischarge the lubricant oil from said lubricant oil transferringmechanism.
 19. The railway vehicle drive unit according to claim 17,wherein said lubricant oil transferring mechanism includes a first pumpto pump up the lubricant oil in response to a positive rotation of saidinput side rotation member, and a second pump to pump up the lubricantoil in response to a negative rotation of said input side rotationmember.
 20. The railway vehicle drive unit according to claim 19,wherein said first pump comprises a first drive gear having teeth aroundits outer diameter surface, and integrally rotating with said input siderotation member, and a first driven gear having teeth meshing with saidfirst drive gear, around its inner diameter surface, and being rotatablysupported by said fixed member, and rotating around a point shifted froma rotation center of said first drive gear to one horizontal direction,and said second pump comprises a second drive gear having teeth aroundits outer diameter surface and integrally rotating with said input siderotation member at a position different from that of said first pump,and a second driven gear having teeth meshing with said second drivegear, around its inner diameter surface, and being rotatably supportedby said fixed member, and rotating around a point shifted from arotation center of said second drive gear to the other horizontaldirection.
 21. The railway vehicle drive unit according to claim 19,wherein said first pump is composed of a drive gear having teeth aroundits outer diameter surface and integrally rotating with said input siderotation member, and a first driven gear having teeth meshing with saiddrive gear, around its outer diameter surface, and being rotatablyarranged on one side of said drive gear in a horizontal direction, andsaid second pump is composed of said drive gear, and a second drivengear having teeth meshing with said drive gear, around its outerdiameter surface, and being rotatable arranged on the other side of saiddrive gear in the horizontal direction.
 22. The railway vehicle driveunit according to claim 17, wherein said input side rotation member hasan eccentric part, said reducing mechanism comprises: a revolutionmember rotatably supported with respect to said eccentric part, toexecute revolution motion around a rotation axis of said input siderotation member; a plurality of rotation regulation members to preventrotation motion of said revolution member, allowing the revolutionmotion thereof; a periphery engagement member fixed to said reducerhousing, to rotate said reducer housing at speed reduced with respect tosaid input side rotation member by engaging with a periphery of saidrevolution member; and a counterweight fitted and fixed to said inputside rotation member with a phase so as to offset unbalance inertiacoupling due to eccentric motion, and said lubricant oil transferringmechanism is provided in said counterweight.
 23. The railway vehicledrive unit according to claim 22, wherein said counterweight includes alarge diameter fun-shaped part, and a small diameter fun-shaped parthaving a radius smaller than that of said large diameter fun-shaped partand connected to said large diameter fun-shaped part in such as mannerthat their chords are in contact with each other, and said lubricant oiltransferring mechanism has an opening part in the chord of said largediameter fun-shaped part, and includes a circumferential oil pathcircumferentially extending in said large diameter fun-shaped part, anda radial oil path extending from said circumferential oil path toward anouter diameter surface of said large diameter fun-shaped part.
 24. Therailway vehicle drive unit according to claim 22, wherein saidcounterweight includes a large diameter fun-shaped part, and a smalldiameter fun-shaped part having a radius smaller than that of said largediameter fun-shaped part and connected to said large diameter fun-shapedpart in such as manner that their chords are in contact with each other,and said lubricant oil transferring mechanism is a fin projecting froman end face of said large diameter fun-shaped part in a thicknessdirection.
 25. The railway vehicle drive unit according to claim 23,wherein said reducing mechanism has a plurality of said counterweightsarranged in such a manner that phases of said large diameter fun-shapedparts differ from each other.
 26. The railway vehicle drive unitaccording to claim 16, wherein said lubricant oil transferring mechanismtransfers the lubricant oil from the bottom region to the upper regionin said space, by use of the rotation of said reducer housing.
 27. Therailway vehicle drive unit according to claim 26, wherein said lubricantoil transferring mechanism is composed of concavo-convex parts formed insurfaces of said reducer housing, and a member rotating with therotation of said reducer housing.
 28. The railway vehicle drive unitaccording to claim 27, wherein said concavo-convex part is a projectionprojecting from an inner diameter surface of said reducer housing andextending in a direction intersecting with a rotation direction of saidreducer housing.
 29. The railway vehicle drive unit according to claim28, wherein said projections are provided in a plurality positions inthe inner diameter surface of said reducer housing, at regularintervals.
 30. The railway vehicle drive unit according to claim 28,wherein a wall surface of said projection opposed to a circumferentialdirection of said reducer housing is in contact with a tangent line ofthe inner diameter surface of said reducer housing, at an acute angle.31. The railway vehicle drive unit according to claim 30, wherein across-sectional shape of said projection perpendicular to a rotationaxis of said reducer housing is an isosceles trapezoid having a longside and a short side parallel to each other, and said short side isarranged so as to be in contact with the inner diameter surface of saidreducer housing.
 32. The railway vehicle drive unit according to claim28, wherein said projection is formed in an inner diameter surface of anannular belt fixed in the inner diameter surface of said reducerhousing.
 33. The railway vehicle drive unit according to claim 27,further comprising: a fixed member arranged in said reducer housing, andconnected and fixed to the vehicle body; and an axle bearing comprisingan inner ring fixed to an outer diameter surface of said fixed member,an outer ring fixed to an inner diameter surface of said reducerhousing, a plurality of rolling bodies arranged between said inner ringand said outer ring, and a retainer retaining an interval of saidadjacent rolling bodies, and rotatably supporting said reducer housingwith respect to said fixed member, wherein said concavo-convex part isprovided in at least one of said outer ring, said rolling body, and saidretainer.
 34. The railway vehicle drive unit according to claim 26,further comprising: a fixed member arranged in said reducer housing, andconnected and fixed to the vehicle body, and an annular seal memberfixed to an inner diameter surface of said reducer housing, to seal aspace between said reducer housing and said fixed member, wherein saidlubricant oil transferring mechanism is a weir expanding from said sealmember to a direction intersecting with a rotation direction of saidreducer housing.